COPII and COPI are considered to be analogous sets of vesicle coat protein hretrocomplexes. Coupled to cargo selection, they mediate the formation of membrane vesicles translocating in opposite directions to different destinations within the secretory pathway. Here, live cell and electron microscopy provided evidence for a different localization and mode of function of the COPII coat during protein export from the endoplasmic reticulum (ER). Pharmaceutical and genetic perturbations of ER-Golgi transport were used to demonstrate that COPII is recruited to membranes defining the boundary of ER-ER Exit Sites (ERES) where it facilitates Golgi-bound selective cargo concentration. Uncoating of COPII membranes precedes cargo accumulation and fission of Golgi-bound carriers. Moreover, we show that anterograde carriers are positive with the COPI complex. These findings change our understanding of the role of coat proteins in ER to Golgi transport.
Keywords: COPII, ER export, ER exit sites, Secretory pathway, ER-Golgi transport
Shomron, Olga and Nevo-Yassaf, Inbar and Aviad, Tamar and Yaffe, Yakey and Zahavi, Eitan Erez and Dukhovny, Anna and Perlson, Eran and Brodsky, Ilya and Yeheskel, Adva and Pasmanik-Chor, Metsada and Mironov, Anna and Beznoussenko, Galina V. and Mironov, Alexander A. and Sklan, Ella H. and Patterson, George H. and Yonemura, Yoji and Kaether, Christoph and Hirschberg, Koret, Early Uncoating of COPII from ER Exit Sites Membranes During Cargo Accumulation and Membrane Fission (May 14, 2019). Available at SSRN: https://ssrn.com/abstract=3387686 or http://dx.doi.org/10.2139/ssrn.3387686
This version of the paper has not been formally peer reviewed.
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